Forest Dynamics and Tree Distribution Patterns in Dry Evergreen Forest, Northeastern, Thailand

Deforestation based on anthropogenic activities is the main cause of biological diversity loss. This study clarified forest dynamics after intermediate disturbances and detected the tree distribution pattern in a dry evergreen forest (DEF). A 1 hectare (ha) permanent plot was set up in a lowland DEF in 2002 and all trees with a diameter at breast height (DBH) larger than 4.5 cm were tagged, measured and identified. Tree monitoring was done in 2009 and 2016. In addition, the permanent plot was expanded to 3 ha, for studying the tree distribution pattern and all trees with DBH greater than 2 cm were included and their coordinates also recorded during 2016. The forest dynamics during 2002 to 2016 showed the net recruitment rate was higher than the mortality rate (2.58 and 2.35 %/year, respectively); however, it varied among periods. The mortality rate in the second period (2009-2016) was greater than in the first period (2002-2009), with rates of 4.71 and 2.64 %/year, respectively, due to disastrous flooding in 2003. A clumped distribution pattern based on the Morisita index was detected for all selected species, indicating habitat heterogeneity in which the physical environments were patched and induced the clumped distribution

Species Composition and Spatial Distribution of Dominant Trees in the Forest Ecotone of a Mountain Ecosystem, Northern Thailand

Plants’ ecological niches are important to study, particularly for applying the knowledge to restoration programs. This study clarified the relationships of tree species composition and spatial distribution to environmental factors in a mountain ecosystem. A 3 ha permanent plot was established across the forest ecotone at Doi Suthep-Pui National Park, Chiang Mai Province, Thailand. The spatial distributions of the 20 dominant tree species were analyzed using a generalized linear model (GLM) combined with geographic information system (GIS) techniques. High species diversity was found, including 165 species representing 118 genera and 59 families. Elevation strongly influenced tree distribution, which could be divided into three groups: low-altitude species in deciduous dipterocarp forest (DDF), high-altitude species in lower montane forest (LMF) and coexisting DDF and LMF species. The GLM analysis revealed that soil texture, which ranged from sandy to clayey, influenced tree distribution. The results suggest that restoration programs should select suitable species based on their niches

Genetic Structure and Population Demographic History of a Widespread Mangrove Plant Xylocarpus granatum J. Koenig across the Indo-West Pacific Region

Xylocarpus granatum J. Koenig is one of the most widespread core component species of mangrove forests in the Indo-West Pacific (IWP) region, and as such is suitable for examining how genetic structure is generated across spatiotemporal scales. We evaluated the genetic structure of this species using maternally inherited chloroplast (cp) and bi-parentally inherited nuclear DNA markers, with samples collected across the species range. Both cp and nuclear DNA showed generally similar patterns, revealing three genetic groups in the Indian Ocean, South China Sea (with Palau), and Oceania, respectively. The genetic diversity of the Oceania group was significantly lower, and the level of population differentiation within the Oceania group was significantly higher, than in the South China Sea group. These results revealed that in addition to the Malay Peninsula—a common land barrier for mangroves—there is a genetic barrier in an oceanic region of the West Pacific that prevents gene flow among populations. Moreover, demographic inference suggested that these patterns were generated in relation to sea level changes during the last glacial period and the emergence of Sahul Shelf which lied northwest of Australia. We propose that the three genetic groups should be considered independent conservation units, and that the Oceania group has a higher conservation priority

Development of 11 polymorphic microsatellite markers for Xylocarpus granatum (Meliaceae) using next-generation sequencing technology

Human impacts have seriously damaged mangroves, and conservation of mangroves will require information on local and regional population genetic structures. Here, we report the development and polymorphism of eleven novel microsatellite markers, developed using next- generation sequencing on 56 samples of widespread man- grove species Xylocarpus granatum (Meliaceae) from nine populations across the Indo-West Pacific region. All loci were found to be polymorphic, with the number of alleles per locus ranging from four to 19. In a population from Sabah (Malaysia), the mean observed and expected heterozygosity per locus was 0.59 and 0.58, respectively. No null allele, significant linkage disequilibrium or deviation from Hardy–Weinberg equilibrium was detected among all loci. The eleven markers developed can be valuable tools to conservation genetics of this species across its distributional range

Vicariance and Oceanic Barriers Drive Contemporary Genetic Structure of Widespread Mangrove Species Sonneratia alba J. Sm in the Indo-West Pacific

Patterns of genetic structure are essential for a comprehensive understanding of the evolution and biogeography of a species. Here, we investigated the genetic patterns of one of the most widespread and abundant mangrove species in the Indo-West Pacific, Sonneratia alba J. Sm., in order to gain insights into the ecological and evolutionary drivers of genetic structure in mangroves. We employed 11 nuclear microsatellite loci and two chloroplast regions to genotyped 25 S. alba populations. Our objectives were to (1) assess the level of genetic diversity and its geographic distribution; and (2) determine the genetic structure of the populations. Our results revealed significant genetic differentiation among populations. We detected a major genetic break between Indo-Malesia and Australasia, and further population subdivision within each oceanic region in these two major clusters. The phylogeographic patterns indicated a strong influence of vicariance, oceanic barriers and geographic distance on genetic structure. In addition, we found low genetic diversity and high genetic drift at range edge. This study advances the scope of mangrove biogeography by demonstrating a unique scenario whereby a widespread species has limited dispersal and high genetic divergence among populations

Taxonomy and systematics of Dendrocalamus (Bambuseae; Poaceae)

THESIS 8441This thesis is concerned with the taxonomy and systematics of Dendrncalamus (Bambuseae; Poaceae). It aimed to assess phylogenetic relationships in the subfamily Bambusoideae and to focus on one highly economically, ecologically and culturally im portant genus, Dendrocalamus. It aimed to provide an account of Dendrocalamus for the Flora of Thailand project, to assess its infrageneric classification and to study the diversity and phylogeography of one of its most important species, D. membranaceus, in Thailand

SITE INDICATOR SPECIES FOR PREDICTING THE PRODUCTIVITY OF TEAK PLANTATIONS IN PHRAE PROVINCE, THAILAND

Site quality assessment is critically important in any tree planting activity as it may serve a range of management functions such as, optimizing productivity estimates of forest plantations. This study aimed to evaluate the site quality, using plant indicators species, for three teak plantations located in Northern Thailand belonging to the Forest Industry Organization (FIO). Twenty-four sample plots were chosen to cover all the growth classes within the age range of 6-39 years. The site index of teak was established by using the anamorphic technique which is based on dominant height and age at a base age of 30 years, divided into 3 site index classes as 24, 21, and 18, as good, moderate, and poor site quality, respectively. Associated species, the native species that are tree and shrub habits, were surveyed in the 24 plots and indicator species were classified using the Indicator Species Analysis (ISA) and Two Way Indicator Species Analysis (TWINSPAN). The relationship between indicator species and environmental factors was analyzed by the Generalized Linear Model (GLM). The associated species was classified into 76 species with 21 families. The results of ISA indicated the significant indicator species under the good site class were Streblus ilicifolius, Lagerstroemia floribunda, Dalbergia cana and Lagerstroemia calyculata; while Schleichera oleosa and Dalbergia nigrescens were presented under poor site class, respectively. The results from TWINSPAN supported Streblus ilicifolius, Lagerstroemia floribunda and Schleichera oleosa were obvious indicators.  Each indicator species distribution influenced by various relationships with environmental factors, which soil pH and N were the main factors to distribute all indicator species to 3 relationships. First, the indicator species positively associated with soil pH and negatively associated with N were Streblus ilicifolius and Dalbergia nigrescens. Second, the indicator species positively associated with soil pH and N were Lagerstroemia floribunda and Schileichera oleosa. Third, the indicator species negatively associated with soil pH and positively associated N were Dalbergia cana and Lagerstroemia calyculata. The GLM analysis revealed P, Ca and elevation influenced indicator species distribution. As of writing, this is the first study on species indicators for suitable sites of teak in Thailand. Meanwhile, in the absence of confirmatory studies, these indicators can be used as guide for farmers interested in planting teak. In bare lands, the farmer can apply these indicator species to determine the site quality based on the species’ past appearance

Arundinella kerrii and Dimeria kerrii , Two New Endemic Species from Thailand (Poaceae, Panicoideae)

Volume: 21Start Page: 149End Page: 15

Effects of Fire on Diversity and Aboveground Biomass of Understory Communities in Seasonally Dry Tropical Forest in Western Thailand

Fire is a necessary disturbance in tropical deciduous forests, as it helps clear the understory community and allows regeneration of grasses and forbs for local wildlife. Huai Kha Khaeng Wildlife Sanctuary (HKK) and Huai Thab Salao-Huai Rabum Non-Hunting Area (HTS) are parts of a few places in Southeast Asia with deciduous forests. However, this area was heavily logged up until 1989, followed by a long period of fire suppression. The consequences of these changes on understory communities have not been investigated. Therefore, the current study aimed to examine the understory communities and their aboveground biomass before and after the annual prescribed burns in HKK and HTS. Understory plant composition and biomass were surveyed in November 2018 (before the fire) and May 2019 (three months after the fire) in 128 temporary plots, covering of deciduous dipterocarp forest, mixed deciduous forest, mixed deciduous forest with bamboo, and open area. We identified a total of 480 understory species, including 37 grass species, 214 forb species, 73 shrub species, 153 tree seedling species and three species of bamboo in the study plots. Grasses in the DDF plots were at 72.79 ± 22.41 kg ha−1, accounting for only ten percent of the understory plants in the plots. The understory community in the DDF plots was dominated by shrubs and tree seedlings of competing species, especially after the fire. The results suggested that past logging activities and long-term fire suppression had reduced the number of mature key dipterocarp forests and hindered the regeneration of grasses and forbs. Maintaining the structure of dipterocarp forests and sufficient food sources for the local wildlife species will require more active habitat management of the study areas